Wireless/Wired Network disconnects.
 

DearAll,
I use Ubuntu on my laptop. The wireless/wired network disconnects and to reconnect to the network I have to restart networking.
sudo /etc/init.d/networking restart

After network restart. , things work fine for next five minutes and disconnects from the network again.
I use statis IPs in all cases.

:/etc/network$ cat interfaces
iface ath0 inet static
address 192.168.1.18
netmask 255.255.255.0
gateway 192.168.1.1
wpa-psk 86c453d5a989ec27b684221eee25ce1476af5a1439e5f87d584f0d3200f093c3
wpa-driver wext
wpa-key-mgmt WPA-PSK
wpa-proto WPA
wpa-ssid NetRack

auto ath0


I dont know what is the error and suspect some damaged files.
Can I reinstall the network to work fine.
Cheers,
Abhinesh